Sheet metal assembly tool and method



Dec. 28, 1965 WIDMAN 3,225,432

SHEET METAL ASSEMBLY TOOL AND METHOD Filed Jan. 51, 1963 INVENTOR ERW/NA. MDMAW United States Patent 3,225,432 SHEET METAL ASSEMBLY TOOL ANDNETHOD Erwin R. Widman, 8615 Elmhurst Ave., Elmhurst, N.Y. Filed Jan.31, 1963, Ser. No. 255,368 Claims. (Cl. 29-429) This invention relatesto sheet metal fabrication techniques and, more particularly, to a noveltool and method for facilitating the assembly of sheet metal parts.While it may have other uses, the invention Was made while attempting toovercome a familiar problem as arises whenever sheet metal duct lengthsof rectangular cross-section must be assembled, and therefore theinvention will be described in connection with such use.

In fabricating rectangular sheet metal duct lengths, it is common toassemble four sheet metal strips into the desired rectangular shape andto joint the same by any of the common types of folded seams along theirconjoining longitudinal edges. Each of those two strips which form thetop and bottom walls of the duct is known as a cheek, and each of thosestrips which form the sidewalls of the duct is known as a wrapper.

In one usual type of duct seam construction, each cheek has a simpleturned down flange along each of its longitudinal edges and each wrapperis folded along each of its longitudinal edges in manner so as to form apocket for receiving the respective of the cheek flanges. The edge foldsof the wrapper are such as to provide an upwardly protruding edge whichis hammered or otherwise turned down on the cheek after the flange ofthe latter has been received in the referred to wrapper pocket. The seamthus formed is more commonly called a Pittsburg type seam, and theinvention will be described in connection with the assembly of ductshaving Pittsburg seams, although it will be understood that theinvention is useful in assembling ducts having other types of seams.

For air conditioning duct Work and the like, it is common to assemblethe duct in sections, sometimes of substantial length. Moreover, theduct sections may be quite high and quite Wide when finally assembled,and it is seen that considerable difliculty is often encountered whenattempting to assemble four sheets or strips of sheet metal into a ductsection by reason of the tendency of the sheets to bend slightly undertheir own Weight and to otherwise misalign while positioning the samefor joining. Even when assembling relatively short duct sections, orthose which do not have particular great height or width, and even wherea special fixture is provided, the work of two men has been requiredheretofore in duct assembly operations.

By the present invention, however, it is found that in most cases onlyone man is required to fully assemble and complete the fabrication ofthe duct, and that no special fixtures or other holding devices, otherthan one or sometimes more of the tools of the invention, are requiredin the work. In addition, it is found that the total time spent by oneman in assembling a duct section in accordance with the presentinvention is usually less than the time spent by each of two men usingpreviously known methods and equipment.

The invention is primarily intended for commercial use where suchsavings in both the number of men and the time required to assemble ductsections or length will in the aggregate substantially reduce the costof sheet metal fabrication operations. The tool as is provided by theinvention is relatively uncomplex and, therefore, economical to make,yet its use in accordance with the method to be described willcontribute to the savings as are elfected through use of the method. Inthis connec- 3,225,432 Patented Dec. 28, 1965 tion, the tool is intendedto accommodate duct cheeks and wrappers of the same or differing widths,as well as those used to fabricate a wide variety of duct sizes.However, the tool may be modified, as will be described, for use in massproduction fabrication operations wherein numerous sections of only onesized duct are to be made.

Briefly describing the present invention, a tool is provided for holdingthe predetermined spacing between the wrappers or side walls of the ductwhile one of the checks is fitted thereon. The tool may be considered ashaving a check guide surface and a wrapper guide surface, each of whichhas a plurality of notches therein. Considering the notches inappropriate pairs, the cheek guide surface notches and the wrapper guidesurface notches respectively receive, for example, both longitudinalside edges of the cheek and the respective conjoining longitudinal sideedges of each of the wrappers during the assembly thereof. The methodinvolves standing both of the Wrappers on edge and placing the wrapperguide notches of the tool in engagement with the respective upstandingedges of the wrappers at generally a middle length location therealongand so as to bridge and hold a predetermined spacing therebetween.Thereupon, starting at one end of the pair of wrappers, the cheek isprogressively fitted into proper conjoining relationship with thewrappers. At the starting end, the longitudinally extending downwardlyturned flanges at one end of the cheek are positioned within therespective pockets which have been previously formed along the wrapperedges, while the cheek flanges at the location of the tool engage andwill be guided by the pair of cheek guide notches of the tool. As thelength of the cheek is progressively assembled into the wrapper pocketsthe tool is moved progressively along the wrapper edges, the wrapperguide notches at the underside of the tool sliding on the upstandingwrapper edges and the downwardly turned cheek flanges being in slidingengagement with the pair of notches at the cheek guide surface at theupperside of the tool. Where the length of duct to be assembled is morethan about four feet, it has been found convenient to use two such toolsin practicing the method, one tool being so placed in engagement withthe wrappers and cheek flanges somewhat near the referred to startingend of the duct and the second tool being so placed adjacent thefinishing end of the duct. Further, it may be found advantageous in someinstances to also position one or two of the tools underneath the loweredges of the upstanding wrappers to hold the predetermined spacingthereat. In such instances, the lower edges of the Wrappers may beplaced respectively in appropriately spaced notches of the cheek guidesurface of the tool.

These and other objects, features and advantages of the invention willbecome more fully apparent from the following detailed descriptionthereof, when taken with reference to the accompanying drawings inwhich:

FIGURE 1 is an enlarged perspective view of the tool provided by theinvention in a preferred form thereof;

FIGURE 2 is a somewhat further enlarged fragmentary perspective view ofthe tool provided by the invention in a modified form thereof;

FIGURE 3 is a view similar to FIGURE 1, but on a smaller scale,illustrating still another modified form of the invention;

FIGURE 4 is a fragmentary view in cross-section of a partiallyfabricated duct section, and showing the tool of FIGURE 1 in positionfor completing the assembly of the duct in accordance with the method ofthe invention;

FIGURE 5 is a side view of the duct of FIGURE 4 during assembly inaccordance with the method of the invention, the view being shown on asomewhat smaller scale;

FIGURE 6 is a top plan view of the FIGURE showing; and

FIGURE 7 is a side view, to a smaller scale, of what may be consideredan extremely long duct section as the same appears when being assembledaccordingto a modified method provided by the invention.

Referring first to FIGURE 1 of the drawings, there is shown a preferredform of the duct assembly tool of the invention, the tool being adaptedas will be described for assembling duct sections of a variety ofwidths. The tool, generally indicated by reference numeral 10, has anelongated body 11 which, in cross-section, has an inverted V-shapedportion 12 and a pair of integrally formed, parallel vertical portions13 and 14. The vertical portions 13 and 14 respectively depend from thelegs 12a and 12b of the V-shaped portion 12, and together provide a pairof underside surfaces 15 and 16 of the tool. Since in accordance withthe inventive method to be described these surfaces 15 and 16 will guideand thereby retain the spacing between a pair of duct wrappers duringassembly of a cheek thereto, they may also be referred to as wrapperguide surfaces 15 and 16. Further, it will be noted that either of theintegrated leg and vertical portions 12a, 13 or 1212, 14 may beconsidered as a means for supporting the body 11 of the horizontallydisposed tool in an upright position during its use as will bedescribed.

A linear upperside surface of the tool is generated by the apex of theinverted V-shaped body portion 12. This surface is indicated byreference numeral 17, and it will later be understood that the surface17 is uppermost during tool use and may also be referred to as the cheekguide surface of the tool.

The body 11 of the tool embodiments to be described is conveniently madeby bending a strip or sheet of sixteen gauge sheet metal to the desiredshape. Moreover, and so that the tool is useful for assembling mostconventional sizes of duct, it has been found that a suitable length forthe elongated body 11 is twenty-five inches (25").

The FIGURE 1 embodiment of. the tool includes a plurality of spacedapart, channel-shaped notches 18 on each of the underside or wrapperguide surfaces and 16. Each of the notches 18 has a rounded bottomportion 18a to facilitate its sliding in contact engagement with an edgeof one of the wrappers, as will be described, and the sidewalls of eachnotch (not numbered) are preferably tapered outwardly towards the openend of the notch. Moreover, each of the notches 18 of either of thesurfaces 15 or 16 is aligned, in transverse direction with respect tothe body 11, with a notch 18 of the other of said surfaces. The spacingapart of the notches 18 along the length of either of the surfaces 15 or16 is the same, and is such that pairs of notches on each surface,considering each notch of the pair as being inward of the respectivelyopposite ends of the surface, are spaced apart a distance which issubstantially equal to the width between wrappers of a conventionalsized duct section. Since duct widths are usually varied in one inchincrements, it has been found that one inch spacing between eachsuccessive notch 18 is satisfactory.

The upperside, or cheek guide surface 17 also has a plurality of spacedapart, channel-shaped notches 19 formed thereon. These notches 19 arepreferably formed bydrill holes through the body 11 along the linearsurface 17, and it will be noted that such drilling provides a roundedbottom 19a of each notch 19, as is desirable. It has also been foundthat each of the notches 19 may be spaced commensurately with thespacing of the notches 18 along either of the underside, or wrapperguide surfaces 15, 16 so that any notch 19 is in transverse alignmentwith a pair of the aforesaid transversely aligned notches 18.

A modified tool 20 having a similarly shaped body 11 is illustrated inFIGURE 3, and it will be noted that the body It has an inverted V-shapedportion 12 providing a linear, upperside surface 17, and a pair ofparallel vertical portions 13 and 14 which depend from the legs 12a and12b of the V-shaped portion 12 and provide the pair of undersidesurfaces 15 and 16. In respect of all of these elements, the FIGURE 3embodiment is identical with that shown in FIGURE 1, and, therefore,these elements are referenced by the same numerals. However, each of theunderside surfaces 15 and 16 has only one pair of spaced apart, channelshaped notches 18, and the linear, upperside surface has only one pairof notches 19, each of the respective notches 18 and 19 being shaped orformed as previously described and, therefore, referenced by numeralsidentical with those for the same notch elements in the FIGURE 1embodiment. Moreover, the corresponding notches of each pair thereof inthe respective surfaces are in alignment in transverse direction of thebody 11, as previously described.

The length of the body 11 of the tool 20 of FIGURE 3 is selected togenerally correspond with the width between wrappers of any one,conventional sized duct section which is to be mass produced, and therespective pairs of notches along its length are spaced apart to conformwith the width between wrappers of the duct section. Thus, the tool 20is adapted for commercial production assembly of duct sections havinguniform width between wrappers.

Another modified tool 30 is illustrated in FIGURE 2. In this embodiment,which is somewhat similar to the FIGURE 1 embodiment as regards itsadaption for use in assembling a variety of duct sizes, the body 21 ofthe tool is of inverted V-shape as might be formed by a length of angleiron, but which also may be formed by longitudinally bending a strip ofsixteen gauge sheet metal to the desired angle at the apex of the bend.Thus, the inverted V- shaped structure provides a pair of undersidesurfaces 22 and 23, and an upperside surface 24 of the tool. Spacedapart, channel shaped notches 18 and 19, as previously described inconnection with the FIGURE 1 embodiment, are respectively located alongthe underside surfaces 22, 23 and the upperside surface 24. Thus,although not preferred, it is seen that the depending parallel verticalportions of the body, as described in connection with the otherembodiments, may under some conditions be eliminated.

Regarding all of the described embodiments, it has been found that thevertical distance measured between the rounded bottom portions 18a, 19aof the transversely aligned notches 18 and 19 should be about one inchin order to avoid undue bending of the duct cheek and to promote ease inthe sliding of the tool along the wrapper edges during duct sectionassembly operations as will be hereinafter described.

The method of the invention will now be described, and for this purposereference is made to FIGURES 4-7 of the drawings.

Referring first to FIGURE 4, the cross-sectional view of a duct section39 which is being assembled clearly shows the duct sidewalls 40 (whichare more commonly referred to as the wrappers) and the top and bottomwalls 42 (more commonly called the cheeks) which are intended to beassembled and joined using a Pittsburgh type joint 44 along each of thefour longitudinally extending edges of the duct section. The Pittsburghjoint when fully formed is as shown at the lower left-hand corner of thedrawing. To form the joint, it will be understood that each longitudinaledge portion 45 of each wrapper is folded outwardly and downwardly, andthen upwardly so as to form a longitudinally extending pocket 46 andprotruding edge 48 therealong. Of course, the pocket 46 might be formedat the duct interior, rather than the duct exterior side of the wrapperas is shown. Along each of the longitudinally extending side edges ofeach cheek there is a downwardly turned flange portion 47 which will bereceived in the comating wrapper pocket 46, as indicated. When the cheekflanges are within the respective wrapper pockets, the upwardlyprotruding edge portions 48 of the wrapper edges 45 are turned down overthe surface of the cheek to complete the Pittsburgh joint.

Prior to assembling such a duct section, each of its four wall sectionsare separate and heretofore it has been found difficult to position thewrappers and cheeks with respect to each other for joining. That is,even where the duct section is relatively short and the respectivewidths of its wall sections are relatively narrow, the handling of thewall sections when attempting to position the downwardly turned cheekflanges within the respective Wrapper pockets is rather cumbersome.Usually the assembly operation requires one man to hold both wrappers ina suitable position while another man progressively fits the cheekflanges within the wrapper pockets. By the method of the presentinvention, however, only one man is required to perform the duct sectionassembly and joining operations. I

In accordance with a preferred practice of the inventive method, arelatively short duct section, having length less than about four feet,is conveniently assembled by first standing one of the wrappers 40upright on one of its longitudinally extending side edges 45 (actuallyon the protruding edge portion 48), and then placing one of theunderside surface notches 18 of the tool in contact engagement with theopposite, upwardly facing protruding edge portions 48, the engagingnotch 18 being one which is disposed near one of the ends of the tool10. By simply holding the tool 10 with one hand, this first wrapper 40is easily held in this upright position.

Using the other hand, which is free, the assembler then stands the otherwrapper upright on one of its longitudinally extending side edges andplaces the same under the tool 10 in generally parallel, spaced-apartrelation with respect to the first wrapper, engaging another notch 18 ofthe tool 10 with the upwardly facing protruding edge portion 48 of thissecond wrapper. The second notch 18 is selected to correspond with thedesired spacing between wrappers in the finished duct section, asindicated in FIGURE 4.

Where such a short length of duct section is being assembled, it will befound that a single tool 10, when so engaging the pair of wrappers, willadequately retain the wrappers in such upstanding, spaced-apart parallelrelation. Where the finally assembled duct section has length of morethan about four feet, it will be found more expedient to place anothertool 10 in similar contact engagement with both of the upright wrappersat another location along the duct section length as indicated, forexample, by the two uppermost tools 10 shown in FIG- URE 7. In anyevent, it will be found that the bridging of the tool or tools 1% acrossthe two wrappers as has been described will be adequate to maintain thewrappers in such standing position so that the hands are free for thepurpose of assembling a cheek to the latter. However, it should be notedthat, for convenience in carrying out the subsequent assemblyoperations, the tool 10 should be located along the length of thewrappers a substantial distance from one end 50 of the duct sectionbeing assembled.

FIGURES 4-6, inclusive, illustrate how a cheek 42 is assembled to a pairof wrappers to form a relatively short length duct section 39. The toolIt is engagement with the respective upstanding longitudinal side edgesof the wrappers maintains the wrappers in proper transverselyspaced-apart relation. The cheek 42 is positioned over the upstandingwrappers so that an end 51 thereof is generally in alignment with theends 54 of each of the wrappers and its downwardly turned flanges 47placed in engagement with that pair of notches 19, at the upperside edge17 of the tool, which are substantially in respective alignment with thetwo notches 18 which are in engagement with the wrappers. The flanges 47at the referred to end 51 of the cheek 42 are then placed in seatedengagement within the respective pockets 46 of the wrap- 6 pers, and itwill be found that in this partially assembled condition the twowrappers and the cheek can be conveniently jockeyed into proper endalignment with respect to each other so as to properly arrange the end50 of the duct section.

Working from the referred to end 50 of the duct section, the flanges 47of the cheek 42 are then progressively fitted within the respectivewrapper pockets 46 along the length of the duct section by simplypushing or pressing on the cheek and progressively moving or sliding thetool 10 along the wrappers in the same direction until the cheek isfully assembled to the wrappers. Of course, by the time this assemblyoperation has been completed, the tool 10 will have been removed fromthe work.

The longitudinally extending, upwardly protruding edge 48 of eachwrapper is then hammered or otherwise turned down over the cheek 42 tocomplete the Pittsburgh joints at this side of the duct section, and thethus partially completed duct section is then inverted so that theopposite longitudinal side edges of the wrapper sections face uppermost.

A tool 16 is placed in contact engagement with the protruding edges 48at the now upwardly facing sides of the wrappers, an appropriate pair ofnotches 18 of the tool holding the spacing between wrappers at alocation therealong which is a substantial distance from the one end 50of the duct section 39, in manner similar to that as has been previouslydescribed. A second cheek 42 is then positioned over the partiallycompleted duct section 39, its downwardly turned flanges 47 being placedin engagement with the appropriate pair of upper-side notches 19 of thetool 10 and with the wrapper pockets 46 at the end 50 of the ductsection, also in manner as has been described. The flanges 47 of thesecond check 42 are then progressively fitted within the wrapper pockets48 along the entire length of the duct section 39, the tool 10 beingprogressively moved in the same direction along the wrappers until theassembling is completed. When the protruding edges 48 of the wrappershave been turned down over this section cheek 42 so as to firmly jointhe latter to the pair of wrappers, the duct section 39 has beencompletely fabricated.

Referring to FIGURE 7, it will be understood that when assembling a verylong duct section 53 the second tool 10, which is more remote from ductsection end 50 than is the first tool 10, also serves to support thecheek 42 at a second location therealong to prevent excessive flexurethereof as might otherwise interfere with the assembly operation.

Also referring to FIGURE 7, it should be noted that one, or perhaps twotools 10 might in some instances be initially used to support theunderside edge portions 48 of the upstanding Wrappers in properparallel, spaced-apart relation when a check 42 has not yet been joinedthereto. As shown, the underside edge portions 48 will engage anappropriately spaced-apart pair of notches 19 on the upperside or checkguide surface 17 of the tool 10, the tool resting on its underside orwrapper guide surfaces 16. Such use of a tool or tools 10 will be foundespecially convenient in circumstances where the width of the wrappersis quite large.

It will also be understood that the tool 30 of FIGURE 2 and the tool 20of FIGURE 3 are used in the same manner as has been described whenpracticig the method of the invention.

Thus, a tool and method for facilitating the assembly of sheet metalparts has been described which achieves all of the objects of theinvention.

What is claimed is:

1. A tool for assembling a sheet metal duct section or the like, saidtool comprising an elongated body having opposite free ends andincluding an upperside surface and an underside surface disposed in thedirection of elongation of said body, underside surface means forsupporting said body in upright position with its said upperside surfaceuppermost, and a pair of spaced apart and transversely disposed guidemeans on said underside surface, each of said guide means beingsubstantially channel-shaped and said pair thereof being respectivelydisposed substantially adjacent said opposite ends of said body.

2. A tool for assembling a sheet metal duct section or the like, saidtool comprising an elongated body having opposite free ends andincluding an upperside surface and an underside surface disposed in thedirection of elongation of said body, underside surface means forsupporting said body in upright position with its said upperside surfaceuppermost, a pair of spaced apart and transversely disposed guide meanson said underside surface, said guide means being substantiallychannel-shaped and said pair thereof being respectively disposedsubstantially adjacent said opposite ends of said body, and a secondpair of spaced apart and transversely disposed guide means on saidupperside surface, each of said second guide means being substantiallychannel-shaped and said pair thereof being respectively disposedsubstantially adjacent said opposite ends of said body.

3. A tool for assembling a sheet metal duct section or the like, saidtool comprising an elongated body having a substantially V-shapedcross-section and including an upperside surface provided by theelongated edge of said body which is generated by the apex of saidV-shape and a pair of underside surfaces provided by the pair ofelongated edges of said body which are generated by the respective freeends of the leg-portions of said V-shape, a plurality of spaced apartand transversely disposed guide means on at least one of said undersidesurfaces, and a second plurality of spaced apart and transverselydisposed guide means on said upperside surface, each of said guide meansbeing substantially channel-shaped.

4. A tool in accordince with claim 3 wherein each of the first saidplurality of guide means comprises means defining a notch of that saidunderside surface on which it is disposed.

5. A tool in accordance with claim 3 wherein each of the first andsecond said pluralities of guide means comprises means defining a notchof that said body surface on which it is disposed, each said notchhaving a rounded bottom portion.

6. A tool for assembling a sheet metal duct section or the like, saidtool comprising an elongated body having opposite free ends, said bodyhaving in cross-section a substantially V-shaped portion and a pair ofparallel vertical portions each depending from an integral with one ofthe legs of said V-shape, said body including an upperside surfaceprovided by the elongated edge of said body which is generated by theapex of said V-shape and a pair of underside surfaces provided by thepair of elongated edges of said body which are generated by therespective free ends of said parallel vertical portions, means defininga plurality of spaced apart and substantially channelshaped notches oneach of said underside surfaces, each of said notches having a roundedbottom and being substantially equally spaced apart with respect to eachrespectively adjacent notch, said plurality of notches of each saidunderside surface including a pair thereof respectively disposedadjacent said opposite ends of the body, and each notch of one saidunderside surface being respectively aligned, in transverse directionwith respect to said body, with a notch of said other underside surfaceto form respective pairs of transversely aligned notches of saidunderside surfaces, and means defining a plurality of spaced apart andsubstantially channel-shaped notches on said upperside surface, each ofsaid upperside surface notches having a rounded bottom and eachrespectively being substantially in alignment, in transverse directionwith respect to said body, with said transversely aligned pairs ofnotches of said underside surfaces.

7. A method of assembling a longitudinally extending topwall sheet to apair of longitudinally extending sidewall sheets wherein said topwallsheet and a longitudinal edge of each of said sidewall sheets areadapted to be joined together, said method comprising the steps ofstanding said pair of sidewall sheets upright and in a predeterminedspaced-apart and substantially parallel relationship with respect toeach other with said respective longitudinal edges thereof uppermost,said predetermined spacing being substantially equal to the transverselymeasured width of said topwall sheet, disposing an elongated tool intransverse direction with respect to said sidewall sheets and placingthe tool in contact engagement at an underside surface thereof with bothof said longitudinal edges of the sidewall sheets at a location spacedaway from one end of the pair of sidewall sheets, said underside surfaceof the tool including a pair of spaced apart and transversely disposedguide means respectively receiving and retaining said longitudinal edgesof the sidewall sheets, and said tool when so engaging said longitudinaledges retaining said predetermined spacing between said sidewall sheets,placing said topwall sheet in contact engagement with the opposite,upperside surface of said tool and substantially in position to bejoined to said longitudinal edges of the sidewall sheets, placing oneend of said topwall sheet in joining relation with respect to both ofsaid respective longitudinal edges of the sidewall sheets at said oneend of the latter, and progressively placing said topwall sheet injoining relation along its length with the respective lengths of saidlongitudinal edges of the sidewall sheets while to substantially thesame extent progressively and substantially sliding said tool along theremaining lengths of said longitudinal edges of the sidewall sheets,said tool always being positioned ahead, in the direction of saidprogressive joining, of the location along the length of said topwallsheet which is then being so joined to said longitudinal edges of thesidewall sheets.

8. A method of assembling a longitudinally extending topwall sheet to apair of lingitudinally extending side wall sheets wherein said topwallsheet and a longitudinal edge of each of said sidewall sheets areadapted to be joined together, said method comprising the steps ofplacing an elongated tool on a work-supporting surface, said toolincluding on its upperside surface a pair of transversely disposedchannel means which are spaced apart a distance, along the length ofsaid upperside surface, substantially equal to the transversely measuredwidth of said topwall sheet, standing said pair of sidewall sheetsupright with said longitudinal edges thereof uppermost and placing therespectively opposite longitudinal edges of said sidewall sheets each,respectively, in contact engagement with said pair of channel means ofsaid upperside surface of the tool, said sidewall sheets extendingsubstantially transversely with respect to the direction of elongationof said tool when so positioned and said channel means of said uppersidesurface of the tool receiving and retaining said opposite longitudinaledges of the sidewall sheets in said spaced apart relation with respectto each other, disposing another elongated tool in transverse directionwith respect to said sidewall sheets and placing the tool in contactengagement at an underside surface thereof with both of said upwardlyfacing longitudinal edges of the sidewall sheets at a location spacedaway from one end of the pair of sidewall sheets, said underside surfaceof the second mentioned tool including a pair of transversely disposedchannel means which are spaced apart a distance substantially equal tothe said transversely measured width of said topwall sheet and each ofsaid pair of channel means respectively receiving and retaining saidupwardly facing longitudinal edges of the sidewall sheets and saidsecond tool, when so engaging said longitudinal edges, retaining thelatter in said spaced apart relation with respect to each other, placingsaid topwall sheet in contact engagement with the opposite, uppersidesurface of said second tool and substantially in position to be joinedto said upwardly facing pair of longitudinal edges of the sidewallsheets, placing one end of said topwall sheet in joining relation withrespect to both of said respective upwardly facing longitudinal edges ofthe sidewall sheets at said one end of the latter, and progressivelyplacing said topwall sheet in joining relation along its length with therespective lengths of said upwardly facing longitudinal edges of thesidewall sheets while to substantially the same extent progressively andsubstantially sliding said second tool along the remaining lengths ofsaid upwardly facing longitudinal edges of the sidewall sheets, saidsecond tool always being positioned ahead, in the direction of saidprogressive joining, of the location along the length of said topwallsheet which is then being so joined to said upwardly facing longitudinaledges of the sidewall sheets.

9. A method of assembling a longitudinally extending sheet metal cheekto a pair of longitudinally extending sheet metal wrappers to partiallyform a sheet metal duct section therefrom and wherein said cheekincludes a downwardly turned flange extending along each of its sideedges and each of said wrappers has a longitudinally extending pocketformed by folds of the wrapper material along a longitudinal edgethereof for receiving one of said downwardly turned flanges of thecheek, said method comprising the steps of standing said pair ofwrappers upright and in a predetermined spaced-apart and substantiallyparallel relationship with respect to each other with said respectlongitudinal edges thereof uppermost, said predetermined spacing beingsubstantially equal to the transversely measured Width of said check,disposing at least one elongated tool in transverse direction withrespect to said wrappers and placing the tool in contact engagement at apair of parallel undersid surfaces thereof with both of saidlongitudinal edges of the wrappers at a location spaced away from oneend of the pair of wrappers, said underside surfaces of the tool eachincluding a pair of spaced apart notches respectively receiving andretaining said longitudinal edges of the wrappers, and said tool when soengaging said longitudinal edges retaining said predetermined spacingbetween said wrappers, placing said downwardly lturned cheek flanges incontact engagement with an opposite, upperside surface of said tool andsubstantially in position to be joined to said longitudinal edges of thewrappers, said upperside surface of the tool including a pair of spacedapart notches respectively receiving and retaining said downwardlyturned flanges of the cheek, placing the respective of said downwardlyturned flanges of the cheek at one end of said cheek within saidrespective pockets of the wrappers at said one end of the wrappers, andprogressively placing said check flanges along their lengths within saidrespective pockets along their lengths while to substantially the sameextent progressively and substantially sliding said tool along theremaining lengths of said longitudinal edges of the wrappers, said toolalways being positioned ahead, in the direction of said progressiveplacing of the cheek, of the location along the length of said cheekwhich is then being so placed within said respective pockets of thewrappers, and said downwardly turned flanges of the cheek always beingin said contact engagement with said tool.

10. A method in accordance with claim 9 comprising the further step ofplacing a second said tool in the same said contact engagement with saidcheek and both of said longitudinal edges of the wrappers, said secondtool being positioned at a second location spaced a substantial distancealong the lengths of said wrappers away from the first said tool in saiddirection of progressive sliding movement of the first said tool.

References Cited by the Examiner UNITED STATES PATENTS 1/1949 BennettD57l 3/ 1954 Lorentzen 2927t1

7. A METHOD OF ASSEMBLING A LONGITUDINALLY EXTENDING TOPWALL SHEET TO APAIR OF LONGITUDINALLY EXTENDING SIDEWALL SHEETS WHERIEN SAID TOPWALLSHEET AND A LONGITUDINAL EDGE OF EACH OF SAID SIDEWALL SHEETS AREADAPTED TO BE JOINED TOGETHER, SAID METHOD COMPRISING THE STEPS OFSTANDING SAID PAIR OF SIDEWALL SHEETS UPRIGHT AND IN A PREDETERMINEDSPACED-APART AND SUBSTANTIALLY PARALLEL RELATIONSHIP WITH RESPECT TOEACH OTHER WITH SAID RESPECTIVE LONGITUDINAL EDGES THEREOF UPPERMOST,SAID PREDETERMINED SPACING BEING SUBSTANTIALLY EQUAL TO THE TRANSVERSELYMEASURING WIDTH OF SAID TOPWALL SHEET, DISPOSING AN ELONGAGED TOOL INTRANSVERSE DIRECTION WITH RESPECT TO SAID SIDEWALL SHEETS AND PLACINGTHE TOOL IN CONTACT ENGAGEMENT AT AN UNDERSIDE SURFACE THEREOF WITH BOTHOF SAID LONGITUDINAL EDGES OF THE SIDEWALL SHEETS AT A LOCATION SPACEDAWAY FROM ONE END OF THE PAIR OF SIDEWALL SHEETS, SAID UNDERSIDE SURFACEOF THE TOOL INCLUDING A PAIR OF SPACED APART AND TRANSVERSELY DISPOSEDGUIDE MEANS RESPECTIVELY RECEIVING AND RETAINING SAID LONGITUDINAL EDGESOF THE SIDEWALL SHEETS, AND SAID TOOL WHEN SO ENGAGING SAID LONGITUDINALEDGES RETAINING SAID PREDETERMINED SPACING BETWEEN SAID SIDEWALL SHEETS,PLACING SAID TOPWALL SHEET IN CONTACT ENGAGEMENT WITH THE OPPOSITE,UPPERSIDE SURFACE OF SAID TOOL AND SUBSTANTIALLY IN POSITION TO BEJOINED TO SAID LONGITUDINAL EDGES OF THE SIDEWALL SHEETS, PLACING ONEEND OF SAID TOPWALL SHEET IN JOINING RELATION WITH RESPECT T BOTH OFSAID RESPECTIVE LONGITUDINAL EDGES OF THE SIDEWALL SHEETS AT SAID ONEEND OF THE LATTER, AND PROGRESSIVELY PLACING SAID TOPWALL SHEET INJOINING RELATION ALONG ITS LENGTH WITH THE RESPECTIVE LENGTHS OF SAIDLONGITUDINAL EDGES OF THE SIDEWALL SHEETS WHILE TO SUBSTANTIALLY THESAME EXTENT PROGRESSIVELY AND SUBSTANTIALLY SLIDING SAID TOOL ALONG THEREMAINING LENGTHS OF SAID LONGITUDINAL EDGES OF THE SIDEWALL SHEETS,SAID TOOL ALWAYS BEING POSITIONED AHEAD, IN THE DIRECTION OF SAIDPROGRESSIVE JOINING, OF THE LOCATION ALONG THE LENGTH OF SAID TOPWALLSHEET WHICH IS THEN BEING SO JOINED TO SAID LONGITUDINAL EDGES OF THESIDEWALL SHEETS.